1. Field of the Invention
The invention relates to a fluid power transmitting device provided in a vehicle.
2. Description of Related Art
A vehicular fluid power transmitting device provided in a power transmission path between a power source of a vehicle and an automatic transmission is known. This vehicular fluid power transmitting device transmits' torque generated by the power source to an input shaft of the automatic transmission via fluid. One known example of a vehicular fluid power transmitting device is a fluid coupling. A fluid coupling is provided with a pump impeller and a turbine runner. The pump impeller is rotatably driven about an axis by a drive source such as an engine. The turbine runner is rotated about this axis by operating fluid that is pushed out by the pump impeller. In Japanese Utility Model Application Publication No. 05-050202 (JP 05-050202 U) and Japanese Patent Application Publication No. 2010-084852 (JP 2010-084852 A), a torque converter is described as a vehicular fluid power transmitting device. The torque converter is provided with not only a pump impeller and a turbine runner, but also a stator that is arranged between the pump impeller and the turbine runner, in a manner rotatable about the axis.
In this kind of vehicular fluid power transmitting device, an input device such as a damper device or a drive plate that inputs torque from an engine that serves as the drive source of the vehicle to the pump impeller is fixed to a pump shell of the pump impeller by a plurality of set bolts. The plurality of set bolts are screwed into a plurality of set blocks that are fixed to the pump shell at predetermined intervals on the circumference of a circle by welding or the like.
One type of damper that may be used as the damper described above is a damper that has a damper shell that is a damper input member that is connected to the engine, a spring that is an elastic member that is housed in this damper shell, and a driven plate that is a damper output member that is connected to the pump shell. Furthermore, this damper may be provided with a bearing that positions the damper input member and the damper output member in the radial and axial directions. With this type of damper, when the driven plate is used for centering with respect to the torque converter, the damper input member that has a large mass is supported via the driven plate and the bearing. Therefore, the centering accuracy of the damper input member decreases, which is problematic. If the centering accuracy of the damper input member decreases in this way, the mass unbalance when the damper rotates will increase, causing the vehicle to vibrate.